


Nightside

by RedSkyNight



Series: By Night [1]
Category: Transformers - All Media Types, Transformers Animated (2007)
Genre: Alternate Universe - Canon Divergence, Canon-Typical Violence, Fingerfucking, M/M, Mild Painplay, Oral Sex, Other, Panic Attacks, Power Bottom Megatron, Power Dynamics, Self-Esteem Issues, Self-Hatred, Size Difference, Size Kink, Someone get Optimus a hug and a therapist, Sticky Sexual Interfacing, Topping from the Bottom, Wet Dream
Language: English
Status: Completed
Published: 2019-08-20
Updated: 2019-08-20
Packaged: 2020-09-19 06:24:01
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 7,705
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20326570
Author URL: https://archiveofourown.org/users/RedSkyNight/pseuds/RedSkyNight
Summary: night·side/ˈnītsīd/nounthe side of a planet or moon facing away from the sun and therefore in darkness.USthe world at night; activities that take place during the night.Optimus has a problem. A 45 foot tall, massive, Decepticon problem. A problem so unbelievably inconvenient that he should really see a therapist. If only he could stop thedreams...





	Nightside

**Author's Note:**

> Honestly, this is just shameless smut. 
> 
> Warning for a panic attack at the end of the fic, it's not involved with the smut part, but Optimus has a little freak-out when he wakes up.

“Bossbot, look out!” Optimus barely had time to dodge before Megatron sent a burst of energy from his fusion cannon, blasting a hole through a thankfully evacuated apartment building. The Prime cursed their luck, lamenting that whenever the Decepticons tried to offline them, it was always within Detroit’s most crowded areas. From what Sari had mentioned, the police force of the city had a specific unit whose sole duty was to clear humans out of the areas Megatron’s lackeys decided to rip apart. 

Optimus threw himself to the side, grappling to the nearest stable structure, narrowly missing Bulkhead’s frame as it sailed past him and crashed into the side of the destroyed apartment building. Optics wide, he turned to look at where the large mech had come from and was unsurprised to see Lugnut ranting about ‘puny Autobots’ and his ‘glorious leader’s plans’. Putting a servo to his audial, he commed Bulkhead, who seemed to be stuck in the wreckage of the building, rebar pinning his massive shoulders. “Bulkhead, report - do you need help?” 

A couple of nanokliks later, the large technician’s voice crackled across the commlink, and Optimus turned to see him attempting to bend the rebar back, “I uh, could probably use a servo, Prime.” He cut off again, and Optimus could hear the groan of steel from across the street. 

Venting harshly, Optimus commed Ratchet, who disengaged from distracting an enraged Megatron and sped over to the Bulkhead-shaped hole in the wall. This, of course, left the warlord free of distractions, with Prowl and Bumblebee attempting to distract Lugnut and a cackling Blitzwing. Megatron seemed to take his chance and was striding across the construction-site-turned-makeshift-battlefield to where Optimus was perched. 

“Oh,_ slag_.” He shot off his grappling hooks again, swinging out of range of Megatron’s massive servos, or so he thought. He hadn’t quite made it to a new perch when he heard the roar of thrusters kicking on. Optimus’s tanks flipped over, feeling his spark pulse a wave of knowing fear to his processor. The Prime swung his axe out blindly, almost feeling the heat of the Decepticon leader’s engines on his back strut. His aim struck true, the axe burying itself in Megatron’s forearm, but it wasn’t enough to stop the bigger mech. Megatron wrenched his arm back, pulling Optimus’s frame taunt, caught between his grapplers and his axe, and a sinking horror filled him as he felt his grapple hook slipping from its spot. Megatron used Optimus’s grip on his axe to secure a grasp on him, curling a servo around the young Prime’s tapered waist. 

Megatron killed his thrusters, his massive pedes fracturing the asphalt road beneath him as he swung his frame around to pin the Autobot against the closest wall. Pieces of broken brick and dust rained down on Optimus’s armor, and he was left staring into the warlord’s optics, pushing futilely at all of Megatron’s vast strength. 

The warlord’s grip curved tighter at Optimus’s squirming, black digits pricking his armor beneath their sharp points. “We meet again, little Autobot.” Something like a smug smile pulled at the corner of his lips, so condescending and lordly it made the Prime’s finials twitch in annoyance.

“Megatron…” There was no turning away from that bright gaze, nailed to the spot with a ticklish sort of fear that wasn’t _all_ fear - Optimus pushed that thought away in a hurry, pulling at his axe, still lodged in the Decepticon’s forearm, a slow trickle of energon dripping from around the glowing blade. 

Where Optimus was expecting to be crushed, pressed to nothing between the immense power of that warbuild force, he was instead being pressured under Megatron’s scrutinizing stare, optics seeming to scan his frame from where he was held. Megatron quirked an optical ridge. “Seems like you’ve gotten yourself stuck in-” a pause, and Optimus could _feel_ the weight of the warlord’s look tracing his frame, “_-quite_ the position, hmm?” 

Optimus snarled indignantly, trying to summon up enough anger to outweigh the way his spark twisted at the warlord’s scrutinization, and planted his pedes on Megatron’s chestplates, pushing him back. Undeterred, he slammed Optimus into the wall with more force, and the Prime could feel the give of the structure behind his back strut. 

“Don’t be like that, I just want to… talk.” That smile was back, and Optimus didn’t trust it. One. Bit. No matter how attractive it made the bigger mech look. 

“Talk about what? Your insane aim to tear apart Detroit with your zealots?” 

Megatron scoffed. “The damage to this city is collateral; do you believe I care enough about these fleshlings to bother destroying them?” he adjusted his grip, digits carving little divots into Optimus’s waist. “No, not that. Not today, at least. I was thinking something more…” The warlord shrugged one massive shoulder, looking smooth and graceful despite his ungainly size, “..._personal_, I suppose you could say.” 

One of Optimus’s optical ridges arched, mouth drawing into a tight frown beneath his battlemask. “Like what, our plans? I’d never give them up to you, Megatron.” 

Megatron’s servo curled tighter, teetering on the edge of causing pain, something uncomfortable thumbing for a split second just along his spinal strut with a _pop_! and a `WARNING: FOREIGN PRESENCE DETECTED` on his HUD before disappearing. Optimus’s vents stuttered at the pressure, mindless exhilaration zinging through his processor at the rough handling. “That’s _Lord_ Megatron to you.” The warlord’s free servo came up to plant itself on the wall next to his chest, leaning in closer than Optimus was truly ready to handle. He was suddenly extremely grateful for his mask, seeing as it hid the flush of energon suddenly rushing through his processor, probably turning his faceplate an embarrassing purple. 

Oh, Primus, he was weak. But Megatron wouldn’t exert his control so easily. “I’ll never call you ‘Lord’ - stop _touching_ me.” 

Megatron, caught in the act, his thumb brushing over the smooth plating at Optimus’s waist, quirked an optical ridge, voice cocky. “I don’t see you trying to stop me.” And damn it all to the Pits, Optimus _wasn’t_, he was dangling in the warlord’s grip while the sounds fighting raged around him and he was still _stuck_, staring into crimson optics and trying valiantly to convince his processor that this was _completely not arousing, so please deactivate the power shift to his interface array, thank you very much_.

“What do you want, Megatron?” Optimus shot back, optics angled in annoyance, desperately trying to control his runaway spiral of conflicted arousal. 

Megatron smirked, “Come again?” _Fragger_.

“What do you want, _Lord Megatron?”_

__

“Ah, now that’s better. See how easy it is to follow instructions from me?” the warlord was grinning with something like victory, and Optimus wanted to cringe away from the indecency of it. 

Or, his traitorous interface protocols suggested, _he could lean into it, see if the Decepticon was implying what Optimus_ thought _he was._ The Prime shoved that thought aside, ruthlessly killing the half-online programming that indicated everything about this situation was desirable, summoning all his mental and emotional fortitude to spit out: “Shut - shut up! Just tell me what you want!” _Smooth, Optimus. Real smooth._

Apparently, his slight loss of temper seemed to be what Megatron wanted. His smile was close-lipped but satisfied, his free servo leaving the wall to brush down Optimus’s chest, down to where his other servo curled around the Prime’s waist. Optimus spluttered, embarrassed and still ignoring his rampaging interface protocols. “As I told you, it’s something personal.” the warlord tilted his helm, listening to something. A comm. “I’m sure I could get what I wanted, but not now. Perhaps another time.” He lowered the Prime, setting him back onto his pedes with a surprisingly light servo. 

Optimus grit his dentae. “Another time-? _Ugh_, no! I won’t play games with you.” Optimus stepped forward to follow him, but Megatron sent him crashing back into the wall with a well-placed jab of his knee. 

“No need to get upset, we’ll have time to talk about it when we next meet.” Megatron waved an imperious servo distantly, already taking massive steps away from him, following his underlings, who had clearly completed their task at the construction site. 

Optimus, shuttering with some unholy rage at being brushed off - well, rage and a sudden and inexplicable pang of hurt at being brushed off - made to run after the warlord, wanting answers even if it meant he would get his skidplates handed to him. He drew up short when something whistled through the air, burying itself into the wall a digit’s-breadth from his helm. His axe. 

“Don’t think too much of me, Optimus Prime.” And then Megatron rose into the air, transforming and taking off, unaware of the turmoil he had left the Prime in. 

Or at least, Optimus _hoped_ he was unaware. 

Optimus practically collapsed onto his berth, feeling sorer than he could have ever thought possible, though he supposed having a Decepticon warlord nearly crush him through a building was enough to cause the discomfort that speared him straight down to the soft protometal hidden beneath his outer armor. He vented, ignoring the twinges of discomfort in his chassis where Megatron had crumpled the metal like paper, folding it beneath the impressive strength of his servos. There were little gouges just above his hips, extending along up his front from where the Decepticon’s claws had dug in, curling around him with all that vast power. Optimus traced a digit along the edge of one of the punctures, tanks flipping at the ache of it. 

It wasn’t a sharp pain, not anymore. The true hurt had faded when the little trickle of energon stopped flowing from them, leaving Optimus with the near-relaxing soreness of a healing wound. Ratchet had tried to insist on treating his injuries as soon as they arrived back at base, but one look at Bulkhead’s damaged helm - not to mention Bumblebee and Prowl’s scorched plating from their close call with an angered Blitzwing - and the old bot relented, allowing Optimus to retreat to his room with a promise to come back to the medbay as soon as he woke from recharge. 

The Prime found he didn’t mind all that much, and felt a brief stab of self-deprecating humor at the thought of him _enjoying_ wounds left by _Megatron_, of all mechs. But, that wasn’t exactly a new thought, nor was it the first time that Optimus had enjoyed the exhilarating thrill of a little pain across his neural net. Megatron was a full-contact fighter - Optimus’s favorite kind - and he seemed to revel in hearing his own voice, especially when he managed to get his faceplates near Optimus’s sensitive audials. His servo-heavy, close-quarters style often left the Prime reminded of his time in the Autobot Academy, when his class had spent time watching holotapes from the war, when Optimus - then a Minor - had been _mesmerized_ by Megatron’s fighting, even as he watched him blast through Autobot troops like they were paper-thin. Those tapes had always filled him with a horrified sort of guilty arousal - it was so wrong, but he couldn’t _help_ it - the way his HUD would come alive, his interface protocols pinging him in need. Optimus had spent megacycles back at the Academy listening to the warlord’s heavily censored speeches, not for the words, but simply for the sound of the mech’s _voice_. In class, it had often been described as one of Megatron’s more _convincing_ qualities, the silver-tongued guile radicalizing young ‘bots before they knew what was happening. 

What no one had prepared him for was how _different_ the Decepticon leader’s voice was when you had a front-row seat to it. He felt ashamed that he couldn't bury the thoughts of Megatron in his processor, never to see the light of day, ashamed that he was glitched enough to find the worst enemy the Autobots had ever had attractive, with his sleek plating and the exotic appeal of his angular face. Optimus crushed that line of thought in his CPU, refusing to further dwell on his apparent weakness as both an Autobot and as a Prime. He offlined his optics and very nearly forced himself into recharge, unaware that his servo had continued to move teasingly along the rough edges of his wounds. 

Of course, it would have been too easy for Optimus to escape his thoughts in recharge. It was during his defragmentation period that most of his thoughts of the Decepticon warlord were brought up, and as of late, due to Optimus's sudden routine of being physically close to Megatron, his processor often ran with his fantasies, attaching to a single string of code generated by his somewhat overactive imagination module. This time was no different, his newest interaction with the warlord proving adept at supplying his unconscious mind with new material for his dreams.

“F-frag, Megatron,” Optimus groaned, static fizzling from his vocalizer as his hips stuttered forward, burying his spike deeper into the massive mech’s overheating body, “so _tight_.”

The Decepticon chuckled, wrapping a servo around the little Prime’s back, and pulled him forward with a low noise of satisfaction, starting up a rumbling purr in his engines. One of Megatron’s digits on his free servo came up to tease the Autobot’s finials, the others almost engulfing his small helm as he curled them. He flicked the sensitive fin away from the Decepticon’s questing servo, but Megatron’s digits followed, stroking the length of it in teasing pulls that left Optimus shivering and sensitive. The Prime was intimately aware of the danger the larger mech presented, especially with his servos wrapped around him like they were. The thought did little to quell his enthusiasm, and he bucked his hips again, trying and failing to bury his pride at watching Megatron’s usually unbothered expression slip to something pleasured, even if it only stayed for a nanoklik. 

“Enjoying yourself, little Prime?” Megatron asked, in a tone that would have been taunting were it not for the staticky jumps that interrupted his normally clear voice. “I would hope so, it isn’t easy, calibrating my frame for a partner with our… _size discrepancy._” Optimus would have risen to that challenge, had he not known that that was exactly what the Decepticon wanted him to do. Instead, he brought a servo up from the warlord’s thighs, running his digits over Megatron’s sticky interface array. True to his word, Megatron has seemed to have recalibrated the components of his array to accommodate the difference in their frames. The Prime bit his lip, tracing the stretched rim of Megatron’s black and red valve, watching another of the glowing blue ridges of his spike slip in, an imperceptible shudder wracking the Decepticon’s chassis. It was _snug_, more than the Prime had thought possible, but the strangeness of it - the dream - was lost on him as he dragged a digit up to Megatron’s swollen anterior node, swirling around it before pressing lightly, teasingly, field awash with heat and want that Megatron met with an aggressive burst of his own. The Decepticon went rigid under the gentle force of the Prime’s touches, back strut arching as he pressed his array down, grinding onto Optimus's spike, nearly buried to the hilt. 

The Autobot vented sharply, feeling steam rise from his overheated frame, stressed in all the right ways, in ways only Megatron could bring out in him. His free servo scrambled for purchase on that sleek grey armor, digits gripping along the edges of the bigger mech’s thigh plating. He teased the sensitive transformation seams, watching Megatron jolt, trunk-like legs wrapping around Optimus, drawing him somehow _closer_, and the Autobot could barely draw back against it. The strength of the mech’s bigger frame was overpowering, intoxicating, thighs squeezing around him and Optimus could _feel_ it, the ache firing up in his sensors as he felt the plating on his hips bend beneath Megatron’s forceful hold. 

He had the sudden, extreme thought that Megatron would crush him, too lost in his own sensation to mind Optimus's smaller build, and the most basic parts of his processor, for some reason, found that _incredibly_ arousing, a drawn-out moan escaping his vocalizer, loud enough to hear over the roar of Megatron’s overwhelming fusion reactor engine. Optimus's optics shuttered closed as he fought off the need to get the Decepticon to wrap tighter around him, to feel his hip struts buckle beneath the stress of all that raw power. Megatron’s legs wound more snugly around him, questing, _ perfect_, and - _oh Primus he could hear the collapse of his pelvic armor_. Faintly he heard a keening, high and pained and blissful all at once, and he recognized it as his own, feeling like he was looking at himself from the outside in. He could feel his charge building, crackling against every sensory node on his frame, arching off him in bolts of blue. 

Then, as quickly as it had onset, the pressure left him, and Optimus slumped over, feeling overcharged but it_ wasn’t enough. _ The servo on his helm curled tight and forced Optimus, finials twitching with charge, to meet the striking red of Megatron’s optics with his own. His processor reeled, taking in the Decepticon’s state, seeming almost overwhelmed himself, and Optimus barely silenced a yelp of surprise when he wrapped a servo around the Prime’s waist and pulled him up to straddle Megatron’s chassis, his spike dripping with their combined lubricants, leaving streaks of pink across the grey plating. He pulled the little Prime closer, until their helms were touching, piercing Optimus through with the force of his stare. The Autobot jumped as Megatron’s other servo wrapped around him, squeezing tightly around his shoulders and waist, irritating the earlier pricks left by his claws. Optimus shuddered on a moan, his cooling fans kicking higher as he reached out, servos clasping Megatron’s helm desperately, the tips of his digits dragging along the sleek grey paint. 

“I believe I have you figured out, little Prime.” Megatron laughed, but it wasn’t mocking, a heady, breathy sound. “You enjoy this?” He curled his digits tighter, and Optimus felt the Decepticon’s claws piercing his armor in new places, and _Primus_ if the feel of energon trickling from the barely-there pinpricks didn’t send a warped pleasure rocketing through his processor. “No, you _love_ this, hmm? That I can control you? That I’m _letting_ you have every inch you take?” 

Optimus would be humiliated with himself when all was said and done, with the way he threw himself at the warlord, desperately crushing their lips together while he whined and ground his spike against that broad grey chestplate. Megatron was _big_ and _warm_ and _perfect_ beneath him, all hard angles and barely masked power and Optimus _reveled_ in it, basking in the heat and _rightness_ of being caught in the warlord’s grasp. A grasp that was currently shifting around his frame, one large servo returning to grip his helm, digits toying with Optimus’s finials as the other servo snuck low to tease over his hot valve paneling. “Open for me, little Autobot,” Megatron whispered against his lips, glossa flicking out to taste him. Optimus was _burning_ and it wasn’t _fair_ and he wasn’t sure if Megatron had meant his mouth or his panel so he opened _both_, sinking his dentae into Megatron’s lip as he shuddered out a moan. 

Then Megatron’s servo was _there_, pressed against the rim of his valve, the broad mass of it concealing his entire array. Optimus bucked wildly into the touch as the warlord rubbed circle around his anterior node, pulsing bright blue at the stimulation. “M-Megatron-!” He tried to escape the servo, his charge ramping up so quickly it sent crackles of lightning skittering over his plating. “It’s - _oooh_ \- it’s too _much_!” But he was still riding that servo like his spark depended on it, so it _wasn’t_ too much, until it _was_ and he was so fired up that he barely felt the tips of two of black digits on him until they were in him, sinking deep as Optimus rocked into the teasing brushes of Megatron’s thumb. It was sudden, the unexpected stretch and give of his valve around two wide digits, and a shock of white-hot pleasure engulfed his neural net. Optimus didn’t hear the noise that must have escaped his vocalizer, too concerned with not blacking out in overload as he stilled his hips, feeling those digits as they curved inside him, relaxing his gripping calipers. 

Then Megatron was sitting up, shifting to lay Optimus back on the berth, one servo smoothing down the Prime’s side, the other still covering his array, digits a steady pressure against the zinging contact points of his valve, thick and _not enough_ all at once. Optimus could feel the ache in his joints as he spread his thighs wide to accommodate the warbuild’s frame, finials flicking back in embarrassment as he watched Megatron’s optics trace down his chassis to leer at him, a self-satisfied smirk plastered on his face. The Prime wanted to be mad at him, but he didn’t even get the chance to bite out an insult before he was thrown headlong back into overwhelming heat as Megatron’s digits pressed against every node in his valve they could reach, stretching him wide as they sunk in to the knuckle. Lubricant tracked down his array, standing out against the black metal of Megatron’s servo. 

“Look at me, little Autobot,” Megatron said, and Optimus onlined his optics, wondering when they had shuttered in the first place. It was so much more humiliating with Megatron _watching_, every sound wrung from his vocalizer only deepening his embarrassment as the warlord stroked the sensitive metalmesh of his valve, his smirk only growing with each noise Optimus made. “Tell me, Prime. Tell me that _this_ is what you want.” A third digit, slick with lubricant, pressed against his rim, slipping in with a wet sound. “What you _crave_.” Optimus gasped, a servo scrabbling at the berthcover while the other clutched fruitlessly at Megatron’s shoulder. “Surrender.” Megatron’s servo pressed tight against his middle, forcing his arching hips to the berth. “_Submission_.” Optimus tried to push back, to gain more _friction_ \- oh he needed just a _little more_, he was _so close_ \- but he couldn’t fight against the force that pinned him. Megatron’s servo traced down his thigh plating, grabbing him around the knee and forcing it to his chest roughly. It _ached_, he _loved_ it. Megatron leered at Optimus. “_This_ was what you needed. A guiding force,” his digits curled, thumb swirling around Optimus’s strobing node, “a _firm servo_ to keep you from straying.” Megatron’s grip curved into his knee joint, pressing deliciously, “Tell me I’m right.” 

Optimus didn’t stand a chance. “You’re right!” he cried, writhing against the warlord’s hold. He bit his lip, tasting energon, one pede on the berth to try and gain just a little traction to force himself down harder on the warlord’s servo. “I need _your_ servos - oh!” he moaned, Megatron’s digits stretching him wide, wide, _wide_, “I need you!” 

Megatron laughed, a lascivious grin pulling at his lips, revealing pointed dentae. “Pitiful mechanism, you look absolutely _obscene_.” 

Optimus certainly _felt_ obscene, legs spread wide to admit Megatron’s bulk, valve stretched around three merciless digits as they pressed deep and opened him up. His spike strained in the air, desperate for any friction he could seek out. He was so charged up it _burned_, the energon in his lines nearly afire. Megatron’s _touch_, his _voice_, it was too much to _bear_. But then the digits left him, petting adoringly at the bright biolights at the rim of his valve. Optimus keened, his hips trying to follow the warlord’s servo, but then both of his legs were suddenly over Megatron’s shoulders, sliding neatly between his neck and shoulder kibble. Megatron grasped him by the hips, lowering himself to the berth as he planted surprisingly gentle kisses against the heated cabling of Optimus’s neck, dragging his mouth against the Prime’s armor as he traced down his chassis. “M-Megatron - _ah-_! What- what are you doing?”

Optimus felt the warlord smile against his inner thigh, nipping at the sensitive protometal as he settled himself between the Prime’s legs, powerful servos settling beneath his hips to lift him closer. “I'm about to give you a lesson in proper oration, little Prime."

“Proper ora_aaah-!_” Optimus’s servos shot forward, latching on to Megatron’s helm, trying not to sound too pathetic, probably failing miserably as a broad, hot glossa lapped at his anterior node, slow and slick and _perfect_. His pedes dug into Megatron’s back, drawing him in closer, feeling the rumble of his laughter against his shuddering frame. 

“So responsive,” Megatron said, partly muffled by Optimus’s thighs - which _wasn’t_ hot, it _wasn’t_ \- and then he was moving into plant kisses over the Prime’s array, mouthing at his spike housing, a flash of sharp dentae as he sealed his lips around the head doing nothing to quell Optimus’s abundant arousal. He wasn’t sure that he’d ever felt this good - this _exposed_ \- before. Megatron was a solid presence around him, so massive and powerfully built that a single servo spanned most of his waist - had _three_ of those digits really been _inside him_?! Primus, how had he _taken_ them? Megatron immobilized him like it was nothing, free servo lifting Optimus’s aft, canting his hip span and curving his spinal strut uncomfortably before he - _oh_! 

“Hah-_ooh_! Mega-Mega_tron!_ I _can’t_-!” He had to be denting Megatron’s helm, but his servos and the warlord’s still glossa were probably the only things keeping him from shaking into an overload then and there. 

Megatron said nothing, humming against Optimus’s valve while his glossa brushed against internal nodes and sensors, coaxing more and more charge from the Prime’s already torqued system. The Prime jolted as Megatron’s nasal bridge brushed over his node, biting down on one of his servos to try and mute the little noises escaping his fritzing vocalizer. That seemed to gain the Decepticon’s attention, because Megatron pulled back and away from Optimus’s valve, digging his digits into sensitive dents when the Prime tried to follow him. 

“Look at me, Prime.” Optimus did. It was a _mistake_, clearly, as his valve cycled down _hard_ on nothing, need shooting through most of his active processes. Megatron, the feared Decepticon warlord, the fragging _Slagmaker_, was smirking between his shamelessly spread thighs, mouth and chinguard glistening with a mess of lubricants. Staring straight back at him. “Perfect. I wish to have your optics on me when I make you overload.”

__

“Megatron, I-” Optimus squirmed in the warlord’s servos, trying not to focus on the heat of the mouth at his valve or the delicious pressure of digits pushing into the dents on his hip struts. Oh, this was _wrong_, he shouldn’t want this, shouldn’t want to straddle Megatron’s leering face and grind his way to a dazzling overload. Shouldn’t want him to be rougher, harder on his frame, until his protoform was achy and he had to pound the dents out of his chassis and hide little crescent sets of punctures from those pointed, wicked fangs. But he _did, oh Primus_, he _did_. He canted his hips toward Megatron, too desperate to be anything other than horribly embarrassing. 

He had half-expected Megatron to pull back more, just to tease him, so the kisses pressed to his bright little node were a surprise that had him shouting, optics flickering as he grasped the berthcovers with shaking digits. Megatron planted more kisses against his valve, sharp dentae grazing the swollen mesh. “Use your _words_, Optimus. I want to know what you _crave_,” he rumbled against the Prime’s array. “I would see you in ecstasy.” Optimus could feel Megatron smiling against him when he clamped his thighs down on that broad helm, drawing him in. Either way, the warlord obliged him, glossa twirling against his node, mouthing at it hungrily. “Or do you want me to guess? To watch you squirm and moan beneath my servos would be glorious.” The flat edge of his dental plates dragged over Optimus’s bright blue node, _hard_. “Don’t think me a fool,” his massive servos ground into dents and sensitive protoform - Optimus’s in-vents were choked, his chassis throbbing sweetly, “you want more - but more of _what_, little Prime?”

Optimus bit his lip. He _shouldn’t_. It was tempting fate already to interface with a warbuild. To ask _this_ of him - but Megatron was massaging circles into every aching component of him, the massive weight of his frame not quite the right amount of pressure. He _knew_, he had to, Optimus wasn’t subtle. He shuttered his optics, humiliated and so, so aroused. “Hurt me.” 

Megatron laughed, long and loud. Optimus had _earned_ it. His servos shifted, palming both of the Prime’s thighs before he grasped them and _wrenched_ them further apart, so quickly that his pedes knocked against the warlord’s massive pauldrons. The stress on his hip joints lit his neural net with dazzling stars, pushed past capacity to the point that Optimus felt a small-scale transformation trigger to prevent damage. The Prime could feel charge jumping from his plating in little arcs of blue light, his fans redlining and _still_ not keeping up with his overheating engine. 

“Keep these spread,” Megatron commanded, voice rumbling through Optimus’s array as his servos slid back up to his leaking valve. Optimus locked his configuration, keeping his straining thigh cables from collapsing into a more comfortable position. Megatron’s red optics flicked up to meet his, glowing in the low light with oppressive approval, “Good, Prime. You follow orders well.” 

Optimus shivered, his plating rattling as the warlord’s thumbs brushed along the rim of his valve, teasing lightly against throbbing blue biolights. “So, little Prime, you want to be _hurt_? I can do that; I can make this delicate frame _ache_.” Megatron’s digits squeezed around the tops of his thighs, blunt-edged claws dragging over his plating, scratching at the paint. Optimus keened, hips bucking as he tried to get more _friction_, something, _anything_ to relieve the pressure that kept building at the base of his spinal strut. “_Oh_, I see…” he said, mouthing at the transformation seams at the edge of Optimus’s array, “the pretty, pristine Autobot Prime has a _fetish_ for warbuilds. Do you like it when you’re _dwarfed_?” 

“Yes! Ah- _yes_!” 

“When you’re helpless?” 

Optimus writhed, doing his best to keep his thighs still, “Megatron, _please_!” His field pulsed, melding with the thick weight of the warlord’s, a foreign lust slamming into his spark under the force of Megatron’s intent. 

Apparently satisfied by the Prime’s desperation, Megatron dipped his helm back down just as his thumbs hooked inside Optimus and _stretched_, the warlord’s lips sealing over his node, a wet, hot glossa flicking over it _hard_. His valve hurt, the stretch almost too much as Optimus ignored the `DAMAGE IMMINENT: PORT CAPACITY 95% ` warning that flashed on his HUD, pushing his hips into Megatron’s grip as he focused on following his orders and _not_ overloading immediately. Megatron’s lips danced over his node, now flashing red and needy beneath the onslaught of attention. The warlord used Optimus’s distraction to duck his helm further, and the Prime ex-vented on a shaky sob when Megatron licked into him, broad glossa lapping up his spilled lubricants as his thumbs toyed with whichever sensitive internal nodes they could reach. 

It was too much. _He_ was too much. Optimus must have been saying so aloud, because Megatron paused, tilting his helm to meet the Prime’s optics, glossa still buried in his spread valve, feeling Optimus’s calipers try to grip him, pull him deeper. 

Megatron must have liked what he saw in the small Autobot’s face because he shifted, glossa slipping back into his mouth, stained with pinkish lubricants, and loomed over Optimus’s frame. His servos slipped away from the Prime’s valve for only a nanoklik before one returned, three digits slipping in _deep_ and fanning, easily besting the clench of Optimus’s calipers and spreading his internals _wide_. Megatron swallowed his cries with a kiss, ducking down to worry the Prime’s lips with his own, glossa sweeping over the sluggishly bleeding cut Optimus had dealt himself earlier before dipping into his mouth, running over his blunt dentae. Optimus shook, back struts arching as he tasted his lubricants, sticky and sweet on the warlord’s glossa. Megatron’s lips left his, peppering kisses down his jaw and neck, tonguing the main energon line down to his shoulder armor. His servo, still pressing into the rolling thrusts of Optimus’s hips, shifted just enough for Megatron to bring his thumb back up to roll over his anterior node, running over it in circles. 

Optimus felt his charge building, more than before, more than he thought he’d ever felt, static rushing through his audials as he grasped Megatron’s helm with both servos, undulating in the massive black servo cupping his paneling. At some point he’d taken up a whispered chant of_ don’t stop, don’t stop, oh _please _don’t stop_ and he only realized because Megatron tilted his helm to the side, pressing in close to smile against the cabling of his neck, teasing and sweet. 

“I wouldn’t _dream_ of stopping, little Prime.” His free servo stroked Optimus’s side, running over the sensitive seams at his waist, digging in and denting the sensitive metal. Optimus sobbed, finials flicking back and forth, helm turning to try and hide his flaring optics against Megatron’s kibble. “Magnificent.” He whispered, lips still pressed to the Prime’s neck, “So good for me.” He kissed Optimus’s neck, glossa a wet heat along his fuel line, _tasting_ him. Then, he bit down. Hard. 

Optimus must have screamed, bright white flares of pain getting wrapped in his desperate arousal, the slick slide of Megatron’s digits inside him. His charge surged, the sharp sting of fangs buried in his neck cables tipping him over the edge in a burst of color and static. He felt his higher processes click offline, legs thrashing as liquid heat rushed through his fuel lines, his valve cycled tight against Megatron’s still working digits. The warlord dragged his overload out, every brush of his digits against his internal nodes sending bursts of electric pleasure over Optimus’s plating. Megatron’s free servo worked his spike, and the Prime whined pathetically as transfluid spilled across his chassis, frame limp and unresponsive in Megatron’s sure grip. 

Optimus’s cooling fans roared, almost drowning out the noise of Megatron’s high-stress engine. The warlord’s frame was hot and heavy pressing down on him, and Optimus flared his plating, smothered and desperate for cool air, but unwilling to give up the crushing presence. He was still running hot, his spike pressurized and trapped between them. He was floating in liquid bliss, still shaking beneath the warlord, his vocalizer fizzling as it tried to reset from the sudden flux in power. 

Megatron gave him a klik, his digits working slowly, easing Optimus through his overload as he twitched, oversensitive and aching with every slide of the thick servo splitting him open. He whined when the digits withdrew, dragging indulgently over his swollen node, feeling wet and exposed as the cool air hit his valve. 

“Now little Prime, fair’s fair.” Megatron shifted his frame on the berth, glossa lapping at Optimus’s neck, over the punctures he’d left there. His servos righted Optimus’s thighs, working the stressed mechanisms until the red and blue Autobot beneath him sighed, frame relaxing. “You did well for me, Optimus. Now, I need you to do even better.” Megatron rose to his knees, straddling the Prime’s waist. 

He met Optimus’s optics, a servo wrapping around his blue ridged spike, “If you depressurize, I’ll offline you - so don’t you _dare_ stop.” 

“Wouldn’t - _ah_\- dream of it.”

If Optimus had planned on saying anything more, it was cut off by a drawn-out moan as Megatron spread his thighs more and dropped himself down on the Prime’s spike. The warlord’s free servo curled into Optimus’s shoulder pauldron, denting the metal easily beneath the crushing force of his digits. His optics flashed brightly, and the Prime could _see_ the sudden charge skitter over Megatron’s grey plating. Optimus hardly faired better, his oversensitive array loudly pinging him that _‘hey, once was enough, you’re breaching standard capacity.’_ He ignored it, hyperfocused on the blazing heat of Megatron’s valve, on the attractive pulse of bright red biolights and dark protometal. 

He ground down on Optimus’s spike, venting heavily as his node brushed the Prime’s spike housing. The image of him - the feared Decepticon warlord that haunted most of Cybertron’s nightmares - legs spread wide, plating flared as he seated himself on an Autobot spike was one that Optimus wouldn’t be forgetting any time soon. He curled a servo around a surprisingly slim thigh, trying not to look to self-satisfied. He probably failed, if the nettled look Megatron shot him meant anything. 

“Not as tough as you like to act, huh Megatron?” his free servo stroked the red biolights that adorned Megatron’s spike, digits teasing the heavily ridged underside. The warlord’s lip curled, revealing gritted dentae. Warm air rushed over Optimus from Megatron’s flaring vent covers as he experimentally rolled his hips down, one servo braced on the berth, the other on Optimus’s thigh. He was looking at the Prime again, a sly smile creeping onto his pale faceplate as he continued rocking his hips down, looking a little too vainglorious to be anything other than uniquely threatening. Optimus internally cringed, knowing he was about to get his comeuppance for thinking he had gained the upper servo on _Megatron_. Maybe he’d been ambitious. 

“I can give you _tough_, little Autobot - can _you_ take it?” 

And then he was doing something _unspeakable_ with his calipers, a rolling clench-and-release that he paired with the rise and fall of his pelvic span over Optimus’s spike. It was ecstatic. It was _unholy_. Optimus was woefully outclassed, his servos denting the metal of Megatron’s thigh, gripping the berth to steady himself. The Prime had never associated the word ‘loud’ with his tendencies in berth, but he was seeing stars now, his oversensitive array alight with sensation while a litany of embarrassing noises spilled over from his vocalizer mixing with even more humiliating speech. 

“Can I-” he stopped, a cracked moan slipping from his vocalizer, oh _Primus_, it was so much Optimus was almost certain that this would be how he offlined. “Frag-! _Oh_, oh Pr_imus_-!” screw whatever he was saying before, it was lost in sensation, lost to Megatron riding him, riding his spike and doing that with his valve. “Mega-” static cut off his oath, his pleading call lost to charge and heat. “Mega_tron_ \- keep go- _ah-_ mm-! Yeah-! Like that,” he rolled his helm back and dug his servos into Megatron’s thighs. “This is per- _ah_! Primus, this is perf- perfect!” Optimus had to restrain himself from bucking his hips upwards, from sinking deeper into the warlord.

Megatron was laughing above him, a heated, dark noise, “Primus isn’t _here_, Optimus - just you and I - so stop praying to an absent god and start praying to _me_.” 

Optimus’s optics flashed, back strut arching as he moaned desperately, needily, servos grasping at Megatron’s thighs, pulling him down harder until the Prime could feel the give of his plating. He was going to overload - it was too much, too quickly and he loved it, hated it, _worshipped_ it. He was so far gone he couldn’t stop the words spilling from his overactive, staticky vocalizer, moans of “Oh frag-!” and “Keep going, _please_, more! Do-_oon’t _ st_op_,” and the way he’d taken up the warlord’s name like a whispered oath, repeating: “Megatron! Oh, oooh Megatron-” over and over until he couldn’t force any words out through the hazy static. 

Megatron’s servo took one of his, prying it out of the dents in the warlord’s thigh and leading Optimus’s digits to the place where they were joined. Optimus took the hint, his digits brushing over Megatron’s flashing node, dipping down to collect lubricant from where it _drip, drip, dripped_ from their heated arrays, and for a moment the Prime’s optics were locked on their hips, stuck looking at the way Megatron’s hot, silky valve gripped at his spike, calipers dragging him back in with a wet, lewd noise every time the warlord dropped himself, aft flush to Optimus’s thighs. He ran his digits back up the soft protometal folds of Megatron’s valve, running a couple of digit-tips in circles around the bright, swollen node, never fully making contact. 

Around him, Megatron clenched harder, grinding his array down with enough force that Optimus could feel a deep, crushing ache in his pelvic span, through the haze of bliss that threatened to short out his processor. It was painful. It was _perfect_. Optimus was moving now, his hips meeting Megatron’s easily, one servo teasing over delicate sensor clusters around the warlord’s valve, the other anchored on strong, black hip plating, forcing Megatron to come down _harder_, be _rougher_ with his already battered plating. 

Optimus faltered briefly, pain shooting through his neural net a little stronger than he anticipated. His grip let up, the roll of his hips a little slower than it had been. Megatron growled, clearly unhappy at the pace change, but at least understood his intentions, and every stroke of his hips landed at least a little gentler than it had. 

Megatron leaned down, frame curling to meet Optimus’s optics, “So fragile, little Prime. You’re like _glass_ under me - if you weren’t such a fun toy, I’d see you _shatter_.” His servos carved divots in Optimus’s abdominal plating, scoring him with sharp claws. _Marking_ him. Optimus, still working his digits around the bright node that gleamed at the apex of Megatron’s dark valve, groaned low and deep, a rumble in his engines threatening to drown out the loud sounds of their arrays meeting. He was so close, but he wouldn’t go over without dragging the warlord with him and redoubled his efforts, digits pressing over Megatron’s pulsing node, the biolight within so charged it was nearly white. His digits slipped over the soft surface of it, wet and sticky with their lubricants, and Optimus watched charge streak up Megatron’s plating, his thighs shaking with strain as he rocked down onto Optimus’s aching spike. 

Optimus was chattering again, aroused and desperate for release, but not without bringing Megatron over too, “I’m so close, please just, just,” he moaned, “a little harder? I can take it, I can do it - want it, want _you_.” His moans rose in pitch when Megatron acquiesced, slowly rolling his hips down harder, brows drawn as he watched Optimus. “Yes, _yes_, perfect.” he moaned, digits sliding over the warlord’s node, trying to pinch it, but it was slippery beneath the tips of his digits, and he lost his purchase before he could do anything but squeeze lightly. Megatron’s whole frame jolted forward, plating clattering in surprise, the grip of his calipers around Optimus’s spike almost unbearable. “Megatron - _oh_, look at me Megatron,” the warbuild did, his optics bright with charge, glossa wetting his lips, “Overload. Overload for me, I want to see it. See _you_.” And Megatron tensed, back arching as he slammed down once, twice, three times and came with a shout, biolights flashing with charge that leapt between the gaps in his dark grey plating. 

His valve cycled down hard, tight around Optimus’s spike, and he was following Megatron over the crest of his second overload, sensitive and jerking, his hips rolling up - drawing more charge out of both of their exhausted systems, and Megatron was looking down at him, softened by post-overload satisfaction. 

“My little Prime, I-” 

  


Optimus woke with a start, heaving himself upright, spark spinning quickly in his chest, armor venting excess heat and frantically trying to cool his overheating systems, still feeling the phantom pangs of the marks dream-Megatron had carved into his chassis. He buried his face in his servos, charge jumping from his finials in electric arcs that only served to make him more ashamed. He felt sticky, and he knew without looking that it was the wetness of his lubricants on his hips and thighs, staining his berth. Disgusting. 

His panel was open, and he felt desperately hot, a phantom ache all over his frame, calling back flashes of his dream where he’d begged for rougher touches, for Megatron to _destroy_ him. In the wake of that vivid fantasy, he curled up, wrapping his arms around his knee guards, trying futilely to drown out the hiss and spit of his vocalizer, fritzing with his turbulent processor. 

He couldn’t go on like this - like he was _broken -_ craving the touch of a mech who’d offline him and everyone he cared about without a second thought. It was wrong. It was _deviant_. If he were on _Cybertron_ \- his digits flexed on his plating, scratching it in self-reprimand - he wasn’t on Cybertron, he was as good as exiled from his home planet. Like the Decepticons. Like _Megatron_. His array pulsed in want, and he collapsed onto his side, curling small and panicked on his berth. He couldn’t deal with this, not while he was awake, not when he _knew_ how wrong it was. How wrong _he_ was. He could ignore it, the charge would bleed off… eventually. His injuries, the real ones he’d gained, throbbed in time with his racing fuel pump, sharpening the ache of pleasure with a little of the pain he craved.

Optimus curled his servos into fists, denting the metal of his palms sick with guilt and shame. He felt dirty, used by his unconscious mind, but he couldn’t imagine dragging himself from his berth, his private room, into the halls to the communal washracks, where someone could catch him, despite the late hour. He bit his lip and choked back a sob that caught pathetically in his vocalizer. Why couldn’t his dreams be normal? Why couldn’t _he_ be normal? 

Far from any place he could call home, call _safe_, the pleasant aura of his dream forgotten, Optimus started at a spot on the wall, counting the minutes on his chronometer. He still had a way to go before morning. 

  
  
  
  


**Author's Note:**

> Check me out on tumblr! https://baneswood-sins.tumblr.com


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